The present invention relates to a motor vehicle driving system including a generator directly coupled to the power output shaft of an engine serving as a power source of a motor vehicle and a motor coupled to an axle and energizable by the electric output from the generator.
In motor vehicles driven by engines which operate at high speeds, the power output of the engines is transmitted to drive wheels through a gear mechanism that reduces the high speed of rotation of the engines Where a motor vehicle is driven by a gas turbine, since the speed of rotation of the gas turbine is about 200,000 r.p.m., the speed reduction ratio must be about 1/200 in order to transmit the power output to the axle.
Japanese Laid-Open Patent Publication No. 59 (1984)-204402 discloses a hybrid automobile having an engine and a motor/generator driven by a battery. The wheels of the automobile are driven by the power output of at least one of the engine and the motor/generator through a torque converter and an automatic transmission. When the automobile is braked, the braking energy is recovered by the motor/generator to charge the battery.
Where the gear mechanism is used for speed reduction, the gear mechanism is complex, large in size, and highly costly because it is required to transmit large torques for driving the motor vehicle. The transmission efficiency of a one-stage speed-reducer gear mechanism is in the range of from 0.9 to 0.95, and hence, the transmission efficiency of a multi-stage gear mechanism used for reducing high-speed rotation is lower, resulting in an increased energy loss.
The proposal according to Japanese Laid-Open Patent Publication No. 59(1984)-204402 is disadvantageous in that the transmission efficiency of the torque converter and the automatic transmission which transmit the power output of the engine or the motor/generator to the axle causes an energy loss.